Hello,
I am maintaining a site. Suddenly, the submit button (all 5 forms) does not trigger anymore.
I have already deactivated all plugins. Did not help either.
Kind regards
Erick
Can you provide a link to a page where we can see the issue?
The page has a JavaScript error:
Uncaught ReferenceError: gform is not defined
Is the PHP dom extension enabled on the server hosting the site? That not being available has caused this issue in the past.
I also noticed the page is cached by WP Fastest Cache.
Caching/optimization plugins and services have been known to cause JavaScript issues. We recommend excluding pages that include forms from those features. See the following page of the documentation for more details: FAQ on Cache and Script Optimizer Issues - Gravity Forms Documentation
The dom extension is enabled and I excluded the page in Wp Fastest Cache.
Still won’t work.
Having a closer look at the page source code, I found the page HTML is invalid, there is another instance of the page header (opening html tag and header markup) in the middle of the page.
That is causing the gform variable to be output in the wrong location, resulting in the JavaScript error.
You’ll need to check the theme template files for what is outputting that extra page header.
There was an override file “header.php”. Same as the original. As soon as I removed the override file, there is only one header. Error gone. Form works again.
You made my day 
. Thank you 